Device for optically recording, digitally, a parameter on a longitudinally moved thread-type material

ABSTRACT

The invention relates to a device and a method for the optical recording of at least one parameter on a longitudinally moved thread-type material. To enable parameters such as the diameter of a thread-type material, the diameter of a yarn package, the hairiness of a yarn etc. to be determined more simply and more accurately, an optical sensor composed of at least two individual sensors ( 30 ), in which at least one individual sensor is so constructed and arranged that at least one measured value is recorded digitally for a parameter, is to be used to record in parallel from the material at least two signals, one at least of which is clocked.

The invention relates to a device for the optical recording of at leastone parameter on a longitudinally moved thread-type material.

There is known from CH 643 060 a method and a device for determining thediameter or the cross-section of a thread or wire-type material. Forthis the shadows cast by the material irradiated by a light source aremeasured on an image recorder, which consists of a number of photocellsarranged next to one another. The photocells emit pulse-type signals,which are evaluated together in an evaluation unit and converted intoactual diameter and cross-section values.

It can be regarded as a disadvantage of this known method that forcertain parameters precise measuring results have to be obtained with acorrespondingly high amount of circuitry, since usable hairiness valuesfor a yarn, for example, can be obtained with it only if the individualphotocells have small dimensions and are provided in suitably largenumbers.

The invention, as it is characterized in the claims, therefore solvesthe problem of creating a device with which parameters such as thediameter of a thread-type material, the diameter of a yarn package, thehairiness of a yarn etc., can be determined more simply and moreprecisely.

The problem is solved by an optical sensor composed of at least twoindividual sensors, in which at least one individual sensor is soconstructed and arranged that at least one parameter is recordeddigitally. Preferably the sensor thus comprises on the one handindividual sensors, which for example record directly digitally aparameter such as the diameter of the material and it comprises on theother an individual sensor which records the same or a differentparameter by analog means. The sensor accordingly comprises individualsensors which operate according to different principles or whose signalsare evaluated according to different principles. Said optical sensor haspreferably an extent which exceeds hat of the material at right anglesto its longitudinal direction and is preferably so constructed hat therecording of a parameter takes place at least partly in the same area ofthe material. the sensors are to be illuminated by directed light, sothat the yarn shades off the light between the light source and thesensor. The sensor is connected to an evaluation circuit with which thesignals from several individual sensors can also be evaluated jointly.

The advantages achieved by the invention can in particular be consideredto reside in the fact that in addition to the diameter of acomparatively smooth material the diameter of a material with a brokensurface structure can also be measured in a differentiated matter,without requiring a device that is of very elaborate construction. Forexample, there can be measured separately on a yarn the yarn package(without projecting fibers) and the hairiness (portion of projectingfibers) of the yarn. Such a sensor can also be adapted to changedmeasurement conditions by means of evaluation electronics and forexample the effect on the sensors of dirt and deposits can be offset orallowed for.

The invention will be described in greater detail below by mean of anexample and with reference to the attached drawings, where FIGS. 1 to 4each show a part of the device according to the invention in asimplified representation,

FIGS. 5 to 8 each show a further part of the device,

FIG. 9 is a diagrammatic view of a function of a part of the device,

FIG. 10 shows an analog and a digital signal,

FIG. 11 shows a cross-section through a thread-type material withpossible dimensions, and

FIGS. 12 and 13 each show a signal from the device.

FIG. 1 shows a sensor 1 which consists of a plurality of individualsensors 2 a, 2 b, 2 c, 2 d etc., which although they are offset relativeto one another, are nevertheless disposed overlapping in certain areaswhen viewed in x direction and in y direction.

FIG. 2 shows a sensor 3 with individual sensors 3 a, 3 b, 3 c, 3 d aswell as 3 e and 3 f, which are arranged in a row. In this case theindividual sensors 3 a-3 d, for example, can operate digitally, whilethe individual sensors 3 e and 3 f can on the other hand operate byanalog means. Thus a sensor 3 is obtained with individual sensors 3 a, 3e which operate according to different principles, at least as regardsthe processing of the signals which they emit. The individual sensorsare arranged in the direction of the parameter to be measured, here, asin FIG. 1, therefore, in the direction of the diameter or cross-sectionof the material K.

FIG. 3 shows a sensor 4 with individual sensors 5 and 6 a 6 k. Here, forexample, the individual sensor 5 can operate by analog means and theindividual sensors 6 a-k operate together digitally, by the individualsignals being combined into a digital signal.

FIG. 4 shows a further sensor 7 with individual sensors 8 a, 8 b and 9a-9 e. As also with the sensor 4 (FIG. 3), the individual sensors 8 and9 cover preferably the same metering section height, or are at leastpartly assigned to the same area of the material (here in y direction).

FIG. 5 shows sensors 10 and 11, which are arranged in two planes 12 and13 inclined relative to one another.

FIG. 6 shows a measuring gap 14 such as is used conventionally for themeasurement or inspection of yarn 15. The measuring gap 14 is bounded oneach side by a cover glass 16, 17. On the other side of the coverglasses 16, 17 there extend focusing hoods or light guides 18, 19, whicheach lead to a transmitter 20, 21 and a detector 22, 23 for lightsignals. The light guides 18, 19 each comprise a mirror 24, 25, so thattwo ray paths 26, 27 are obtained which lead respectively from thetransmitter 20, 21 via the mirrors 24, 25 and the yarn 15 to thedetector 23, 22. The transmitters 20, 21 are preferably constructed insuch a way that they send out light in a main direction. The detectors22, 23 comprise preferably a telecentric optical detection system.Substantially parallel light beams therefore occur in the vicinity ofthe cover glasses 16, 17 and the measuring gap 14. The position of theyarn 15 in the measuring gap 14 can thus change without the size of theimaging of the yarn 15 onto the detectors 22, 23 changing. The scaletherefore remains the same. It is also ensured by this arrangement thatthe orthogonal light beams in the measuring gap 14 scarcely influenceone another and hence can be used simultaneously for the obtaining ofmeasured values.

FIG. 7 shows two identically constructed circuits 28 and 29 such as canbe provided for each individual sensor. One such consists of an element30 for converting light into an electric current, for example aphotodiode. Said element 30 is regarded preferably as an individualsensor in itself. The latter is connected in series with furtherelements for the conversion of its output signal, such as a chargeamplifier 31, 35, a comparator 32 and a storage device or latch 33. Thecharge amplifier 31, which consists of an operational amplifier 31 and acapacitor 34 (in the feedback path), is further connected in parallelwith a switch 34. The comparator 32 is connected with its input to areference circuit 36. The storage device 33 is connected with its outputto a multiplexer 37. There is connected in series with the multiplexer37 in turn an evaluation circuit 38, which can preferably be constructedas a computing element. Likewise connected to the evaluation circuit 38is optionally a circuit 39 for generating an analog individual signal.The latter comprises in addition to an individual sensor 64 inparticular an operational amplifier 61 with a parallel connectedcapacitor 62 and a resistor 63. Preferably at least one part of theaforementioned elements is integrated with the individual sensor 30, 64to form an integrated circuit and thus forms a so-called “smart sensor”.

FIG. 8 shows diagrammatically a surface 40 of one of the sensors, athread-type material 41 in cross-section and a light source 42 fordirected light. Said light source 42 can consist for example of apoint-or line-shaped light source 43 and a telecentric optical detectionsystem 44. Directed and preferably parallel beams 45 can be generatedwith it. FIG. 9 shows various lines which concern operations in thedevice and which are shown above a time axis 46 and next to an axis 47which are entered along the values for electric voltages or percentagesof possible values thereof. Line 48 marks for example the start and line49 the end of a periodic cycle. Lines 50, 51 and 55 indicate thecharging of the capacitor 35 over time in various situations, whichstart with a time corresponding to a line 52.

FIG. 10 shows in simplified form, plotted above a time axis t, an analogindividual signal 57 and a digitized and clocked individual signal 58,which consists of individual values 58 a to 58 f. Due to the differentprinciples which are used in the measurement or evaluation, differentialvalues 59 c, 59 d etc. are for example obtained between the analog andthe digital signal.

FIG. 11 shows a contour 70 of a cross-section of a thread-type material,which contour 70 is here assumed to be noncircular and in particularelliptical in shape. di and d2 are main dimensions, such as aredetermined along the main axes of the contour 60. di′ and d2l are maindimensions such as are determined in two other, orthogonal directions.

FIG. 12 shows a representation of a thread-type material 65 whichcorresponds for example to the material K from FIG. 1, namely arepresentation such as is obtained by individual sensors 6FIG. 3 withcorresponding resolution for example in the evaluation circuit 38, inwhich several successive measurement cycles are stored. Here theindividual sensors, such as e.g. the individual sensor 66, have smallerdimensions than the individual sensors 6 and 9 and there corresponds toeach individual sensor or pixel in a storage device of the evaluationcircuit 38 a storage space which is occupied with a binary signal. Inorder to obtain such a representation, several columns 67 a, 67 b, 67 c,etc. are stored, wherein each column 67 pertains to a particularmeasurement cycle. Next to the actual material 65 and projecting fromit, individual fibrils or fibers can be distinguished, which are labeled68 and 69. The symbol 70 stands for a so-called erosion matrix, which isused for the carrying out of so-called neighborhood operations known perse. The latter consists here of thirteen pixels or storage spaces, whichare arranged around a central pixel 71 on which the neighborhoodoperations is (sic) performed.

FIG. 13 shows a representation according to FIG. 12 in which theprojecting fibrils or fibers are path-eroded by the neighborhoodoperations. Thus there is distinguished now only a large-area structuresuch as the actual material 72 whose diameter is reduced artificially bythe erosion to some two pixels on each side.

The method of operation of the device is as follows:

As shown in FIG. 8, a thread-type material 41 such as e.g. a yarn, afiber, a wire etc., such as is the case for example with known yarntesting units and yarn cleaners, is moved in a measuring gap in itslongitudinal direction past a sensor whose surface 40 is representedhere. The surface 40 is covered or shaded relative to the light source42 by the material 41. Behind the surface 40 a sensor 13, 4 or 7 isprovided, such as is known from one of FIGS. 1 to 4.

With the sensor 1 there can be recorded for example the diameter of amaterial K in y direction or the arrival of a material K in x direction.The material K covers, viewed from the light source in FIG. 1, twoindividual sensors completely and two only partially. Four individualsensors thus each emit an individual signal, which is influenced by thematerial K. Three individual sensors 2 a, 2 b, 2 c emit an individualsignal which is not influenced by the material K. An evaluation of thetotaled eight individual signals enables a signal to be generated whichis proportional to the diameter of the material K. The accuracy of themeasurement depends on the number of individual sensors which areprovided per unit of length or on whether the individual signals areintrinsically modulatable, i.e., are processed by analog means, orwhether they are recorded only in binary form, so that a digital signalis obtained. A further possibility consists in configuring the sensor 1in such a way that it records as a parameter only the position of thematerial K in y direction. Then for example the individual sensor 2 cdoes not emit a signal which indicates shading by the material, whereasthe individual sensor 2 d emits such a signal. An external demarcationof the material K therefore lies between them.

With the sensor 3 (FIG. 2) the diameter of a material can be recorded asa parameter in the same manner as with the sensor 1. If it is assumedthat the individual sensors 3 a 3 d emit individual signals which arerecorded in binary form and that the individual sensors 3 e and 3 f emitindividual signals which are recorded and further processed in analogform, a differentiated recording of edge areas of the material can thusbe made possible. Or the diameter can be recorded with the individualsensors 3 a-3 d and the existence of projecting parts and theirapproximate dimensions be recorded with the individual sensors 3 e and 3f. With the sensor 4 (FIG. 3) the diameter of the material can berecorded on the one hand digitally by the individual sensors 6 a-6 k andon the other in analog form by the individual sensor 5. The individualsensor 5 supplies an individual signal which is proportional to theshading by the material. The individual sensors 6 each supply anindividual signal which, although it is likewise proportional to theshading, is however binarized, so that a digital signal is generatedfrom the individual signals of the individual sensors 6. Comparison ofthe individual signal from the individual sensor 5 with the signal fromthe individual sensors 6 enables further parameters to be determined,such as the hairiness, structure etc. of the material, in particular ifthe material is a yarn.

With the sensor 7 (FIG. 4) the same measurements can in principle becarried out as with the sensor 4, except that the individual sensors 8each emit an individual signal which is dependent on the position of thematerial in front of the individual sensors 8 in y direction. Forexample, if the material is at the bottom edge of the sensor 7, it thenshades mainly the individual sensor 8 b, so that the individual signalof the individual sensor 8 b is influenced far more strongly than theindividual signal of the individual sensor 8 a. If the material is atthe top edge of the sensor 7, the individual sensor 8 a is influencedmore strongly.

With a device according to FIG. 5, in which sensors 10 and 11 arearranged in two planes 12, 13, the material can be viewed from twodirections, which permits more accurate conclusions as to the truecross-section of the material. There are provided as sensors 10, 11sensors 1, 3, 4, 7 or others.

With the device according to FIG. 6 a material, here a yarn 15, canlikewise be viewed from two directions, corresponding to the ray paths26, 27. The transmitter 20 transmits a ray of light onto the mirror 24,which is passed from there onto the detector 23. At the same time theyarn 15 shades the detector 23, which consists of one of the sensors 1,3, 4, 7. The transmitter 21 transmits a ray of light onto the mirror 25,which is passed from there onto the detector 22. At the same time theyarn 15 shades the detector 22, which consists of one of the sensors 1,3, 4, 7. There is understood as a ray of light here a whole bundle ofpreferably directed and parallel rays, so that the yarn 15 is alsodetected if it is not located precisely at the point shown in themeasuring gap 14.

If now an individual sensor is covered partly or completely by amaterial relative to a light source, a cycle takes place roughly asfollows. At a time 48 (FIG. 9) said cycle starts by a reset signal 56being triggered which closes the switch 34 (FIG. 7), keeps the latterclosed and lasts up to a time 52, with which a start is therefore madeon charging the capacitor or capacitors 35 by photocurrents from theindividual sensor or sensors, or in other words on integrating thesignal recorded.

If an individual sensor is not covered by the material 41 relative tothe light source 42, the charging of the capacitor 35 proceeds rapidly,as is shown by the line 50, and is completed at the time 53 if athreshold S4 is reached. The operational amplifier 31 at the same timeamplifies the signal from the capacitor 35 and passes it to thecomparator 32. The latter compares continuously the signal according toline SO with a threshold value which is represented by a line 54 andsits close via a circuit 36. If the threshold value 54 is reached, thecomparator 32 passes a signal to the storage device 33, which signalindicates that the individual sensor is not covered. Said signal hasonly two possible values and is a binary signal.

If an individual sensor is shaded by the material, it does not receiveany direct light, but at best scattered light. The capacitor 3S istherefore only charged more slowly, for example according to a line 55,and reaches the threshold value 54 at best after a very long time whichexceeds the cycle time. The signal recorded is therefore integratedduring a predetermined time and then reset. The storage device 33, whichoperates with the same cycle time and is therefore clocked in synchronywith the switch 34, now receives from the comparator 32 a signal whichindicates that the individual sensor is shaded and said signal can beoutputted together with the signals from the storage devices of theother individual sensors. The multiplexer 37 produces from all thesignals, by mounting the individual binary values side by side, an imageof the illumination of the whole sensor. A value for the yarncross-section can for example be obtained from this.

The cycle time is delimited by the lines 48 and 49. Depending on thequality of the individual sensor or the degree of fouling of theindividual sensor, a greater or lesser time elapses until the chargingof the capacitor 35 reaches the threshold value 54. The lines 49 and 51indicate how long the charging of the capacitor 35 takes if only 50% ofthe possible light reaches the individual sensor. It can be adopted asan approach for the selection of the permitted time for the charging ofthe capacitor 35 that the reaching of the threshold value 54 at halfoutput should still be possible within the cycle and hence the time 49.Due to displacement of the lines 52, 53 within the cycle time, this canbe set by lengthening or shortening the duration of the reset signal 56,which also means that the reset signal 56 takes up the remaining part ofthe time in the cycle. Individual sensors which are not chargedsufficiently in the time between the lines 49 and 52 are thereforeregarded as covered by the material. If the fouling is insignificant andif a particularly good individual sensor is involved, the lines 52, 53can be displaced in the direction of the line 49 and the lines 50, 51can have a steeper course. These operations can be repeated for eachindividual sensor, there being determined as controlled variable thattime which is required for the signal of the first of the individualsensors involved to reach the threshold 54. This time is regarded as theactual value for the control. Doubling the value of this time producesthe illumination or integration time which lies between the lines 49 and52. If the latter is too short, the first individual sensor reaches thethreshold 54 too late, i.e. not until after more than half the time. Thelatter then simply has to be prolonged.

If it is assumed, for example, that with the sensor 4 there is generatedby means of the individual sensor 5 and a circuit 39 (FIG. 7) an analogindividual signal 57 (FIG. 10) which is proportional to the diameter ofthe material, and that there is generated by means of the individualsensors 6 a-6 k-and circuits 29, 30 etc. a digital individual signalwhich is likewise proportional to the diameter of the material, it isfound that the two individual signals do not coincide exactly, even ifthey originate from the same material. Differential values 59 result forexample from the fact that the individual sensors 5 and 6 do not recordedge areas of the material equally. For example, the individual sensors6 record in the case of a yarn rather the yarn package, whereas theindividual sensor 5 records the yarn with projecting fibers. Thedifferential values 59 can for example in the case of a yarn correspondto the hairiness and are determined as such in the computing element 38from the individual signals 57 and 58 by subtraction. Two signals aretherefore recorded in parallel from the same material. One of them isclocked.

With the device according to FIG. 5 the material can be recorded fromtwo directions. If the cross-section of the material is to be determinedas the parameter, two different diameters must be measured for this.There are various possible ways of doing this, as FIG. 11 shows. Maindimensions di and d2 or di′ and d21 can be determined as diameters. Asfor example two directions are predetermined with the device accordingto FIG. 5, which for example are at right angles to one another, theuncertainty as to which dimensions will be recorded remains, since thisdepends on the chance position of the material. In order to reduce thiseffect as much as possible, the two dimensions recorded are to becomputed twice, i.e. the product d1*d2 or d1f*d21 of the main dimensionsand half the sum of the squares of the main dimensions, that is to say0.5(d12+d22) or 0.5(d1′2+d2′2), is to be formed. This can be carried outin the evaluation circuit 38, to which all the individual sensors of thesensors 10 and 11 are connected. There can also be obtained from the twomain dimensions data on parameters such as the roundness (circularity),or in the case of doubled yarns the doubling direction, by for examplecalculating the quotient of the small diameter and the large diameter,e.g. d2/d1.

Preferably the integrating individual sensors 5, 8, which emit an analogindividual signal, are clocked with the same clock signal as theindividual sensors 6, 9, which emit a digital signal. This then producesin FIG. 10 likewise a stepped curve 57 a, which replaces the individualsignal 57. Despite this, however, the stepped curve 57 a is based onsignals recorded and processed in analog form.

The individual signals from the individual sensors can optionally befurther processed by neighborhood operations known per se. For thisfirst of all the results of the digitizing individual sensors 6, 9 fromsome successive cycles are stored. The signals of each individual sensorfrom one of these cycles are recorded together with the neighboringsignals, i.e. the signals of the same individual sensor in neighboringcycles and the signals of neighboring individual sensors in the same andin neighboring cycles, and compared with the relevant signal of theindividual sensor. There is therefore also formed for each individualsignal the environment, and individual signals of an individual sensorimpinging from the environment are adjusted to the surrounding signals.Loose structures consisting of loosely cohering pixels are eliminated inthis way, and only large-area structures, such as e.g. a yarn package,remain, as shown in FIG. 13.

What is claimed is:
 1. A device for the optical recording of at leastone parameter on a longitudinally moved thread-type material, includingan optical sensor composed of at least two individual sensors, in whichat least one individual sensor is so constructed and arranged that atleast one measured value is digitally recorded for the parameter and oneindividual sensor is provided for the analog recording of a measuredvalue for the parameter.
 2. Device according to claim 1, characterizedin that a plurality of individual sensors (2 a-2 c, 3 a-3 d, 6 a 6 k, 9a-9 e) are provided for the direct digital recording of a measured valuefor the parameter.
 3. Device according to claim 1, characterized in thatthe individual sensor (5, 8) for the analog recording and at least oneindividual sensor (6, 9) for the digital recording of a measured valuefor a parameter are assigned at least partly to the same area of thematerial.
 4. Device according to claim 1, characterized in that thereare assigned to the individual sensor for the digital recording,elements (31, 32) for converting its output signal into at least onebinary signal, wherein at least one threshold value (54) is provided. 5.Device according to claim 4, characterized in that the elements (31, 32)are integrated on an integrated circuit with the individual sensor (30).6. Device according to claim 1, characterized in that there is assignedto the sensors a light source (42) for directed light.
 7. Deviceaccording to claim 1, characterized in that an optical sensor (10, 11)is disposed parallel to a first and to a second plane (12, 13)respectively.
 8. A method for the optical recording of at least oneparameter on a longitudinally moved thread-type material, including thestep of recording at least two signals in parallel from the material atthe same location and at the same time, wherein at least one of saidsignals is processed digitally and another of said signals is processedin an analog manner to form a measured value.
 9. Method according toclaim 8, characterized in that the signal recorded in clocked form isintegrated during a preset time and reset after the predetermined time(48).
 10. Method according to claim 9, characterized in that the signalrecorded in clocked form is compared continuously with a threshold value(54) and an output signal is generated if the threshold value is reachedwithin the pre-determined time.
 11. Method according to claim 9,characterized in that the predetermined time is influenced by operationswhich include a light source (42) for illuminating the material and ischangeable thereafter.
 12. The method according to claim 8, in which thesignal that is digitally processed is clocked.